Hybrid electric vehicles having an internal combustion engine combined with an electric motor-generator and an electrical energy storage system have been the focus of considerable attention in the automotive field. Hybrid electric vehicle systems are, however, only recently attracting significant interest for use in commercial vehicles, e.g., freight trucks.
For drivers of these commercial vehicles, federal, state and local laws, as well as private policies, regulate the length of driving shifts, as well as the frequency and duration of rest breaks between shifts. These policies are in place as safety measures to prevent driver fatigue.
It is for this reason that commercial motor vehicles are often equipped with sleeper berths, which are used by drivers during these rest breaks to sleep or otherwise rest. These sleeper berths are generally equipped with the conveniences of heating, air-conditioning, electric appliances, and other comforts. These and other hotel loads (i.e., non-propulsive electric loads) are typically powered by one or more of the following power sources: auxiliary power units, fuel fired heaters, on-vehicle electric storage systems (“ESS”) and from a rest facility source. Auxiliary power units are typically combustion engine-driven electric generators and air-conditioning units that use power from a diesel engine to cool the sleeper berth and power the appliances. Fuel fired heaters burn diesel fuel to heat the sleeper berth. On-vehicle electric storage systems offer pre-charged sources of electric power that is typically charged by regenerative means, engine power or stationary power sources.
The application of hybrid electric vehicle systems to commercial vehicles provides the ability to use the hybrid electrical energy storage system to power vehicle electric loads.
U.S. Pat. No. 8,548,660 discloses a hybrid vehicle charging system that, during periods of driving, uses driver profile information, GPS information, environmental information, accessory information and system default parameters to generate a strategy for managing stored electric energy in order to power electric loads of the vehicle. But this prior art does not address predicting electrical power needs during rest breaks when the driver is not driving the vehicle. It also does not address ensuring sufficient electrical power is available at the beginning of the rest break in order to meet those predicted needs. Nor does this prior art take into account the need to ensure sufficient electrical power is present after a rest break to operate the vehicle.
If a hybrid vehicle's electrical energy storage system is to be used to power sleeper berth hotel loads during rest breaks, it is beneficial to ensure that—prior to the rest break—the amount of electrical energy stored is sufficient to power the hotel loads for the entire period of the rest break. It is also beneficial to ensure that the amount of electrical energy remaining after the rest break is sufficient to resume driving.